1. Field of the Invention
This application relates generally to signal processing and more specifically, but not exclusively, to leading edge detection.
2. Relevant Background
Distance ranging involves determining (e.g., estimating) a distance between two locations. A ranging device measures the distance from the ranging device to another object through the use of various technologies such as laser, radar, sonar, or various forms of radio-frequency (RF) signaling. For convenience, the term distance ranging will be referred to herein simply as ranging.
To estimate the distance to an object, a ranging device determines the amount of time it takes for a signal to travel between the ranging device and the object. For example, a ranging device may measure the time it takes for a signal to travel to the object, reflect off that object, and travel back to the ranging device. Accordingly, the ranging device will record the time that it sends a signal and the time that the reflected signal is received back at the ranging device. The ranging device may then estimate the distance based on the signal propagation time and the known propagation speed of the signal (e.g., estimated as the speed of light).
In some cases, a two-way ranging scheme may be employed to determine the distance between two devices. Here, a first ranging device may determine the distance to a second ranging device based on a round-trip time associated with signals transmitted by the ranging devices. That is, in a two-way ranging scheme, the first ranging device sends a signal to the second ranging device and, in response, the second ranging device sends a signal to the first ranging device. To determine the round-trip time, each ranging device records the time at which that ranging device sends a signal to the other ranging device and the time at which that ranging device receives a signal from the other ranging device.
In some aspects, the accuracy of a ranging measurement depends on the accuracy with which a ranging device is able to determine when a signal is received (e.g., the time-of arrival of a signal). Accordingly, a need exists for effective techniques for determining the time-of-arrival of a signal.